Do all iPhones get IOS releases at the same time regardless of carrier? (Not a rhetorical question -- I honestly have no idea how iOS upgrades work.)

It is indeed a bit ridiculous that you have to not only have the right phone but also be on the right carrier (or, more accurately, be on the right radio technology) to get timely updates. I wasn't expecting my CDMA Nexus S to get Jelly Bean any time soon, but everyone who has a Galaxy Nexus should have gotten it from day one, not just the GSM owners.